I did Carnedd Llewelyn on Tuesday from the Ffynnon Llugwy Reservoir road and managed to descend all but a couple of hundred paces on skis, to within 10 meters of the car parked at the bottom of the reservoir road.
I ascended all the way on skins, except the short section of the road that is covered in sheep feed and poo!

I would say conditions were good! I used my old skis and skins, but barely touched a rock.

I went up via the road, crossed the Afon Llugwy via the bridge just below the Reservoir. Up the fence towards Creigiau Hirion then struck northwards above Craig y Llyn. I traversed beneath the foot of Craig Llugwy and around the cwm to reach Bwlch Cyfryw-drum between Carnedd Dafydd and Carnedd Llewelyn. Along the ridge and up the South and then South East face of Carnedd Llewelyn as there were less exposed stones here than the main path.

I descended the South West face towards Cwm Llugwy over hard rime snow. At the most convex part of this slope there is a 3 inch layer of windslab, which was strong(hard to deform an unisolated section with body wieght on skis), but weakly bonded benealth with a very fluffy layer on snow on top of an older harded packed layer. I don't suppose there is a history of avalanches here, but I don't suppose many people have been at this point to act as the trigger!

Just before reaching Craig y Tri Marchog I traversed Cwm Llugwy to reach the broad spur between Craig Llugwy and Craig y Llyn, the slope down to the wall gave further sport untill a couple of hundred paces of rocks are reached. These could be carefully skised but I carried skis here to be on the save side. A quick shuffle over the bridge and along the track brought me to the road and a rapid descent back to the car.

Some other folks skinned up Pen yr Helgi Du the day before. This apparently gave a good descent of Y Braich, turning right at about 650 meters to follow a shallow steeper depression to the right of a fence line, before crossing the wall to whoop down the road.